The present invention relates to filler tubes for motor vehicle fuel tanks and the problems related to controlling emission of fuel vapors therefrom during refueling operations.
Currently, it is required to provide for controlling the emission to the atmosphere of fuel vapor during refueling when a nozzle has been inserted into the fuel tank filler tube for discharging fuel into the filler tube. Currently, vehicle fuel tank filler tubes are designed to have a baffle in the filler tube with a flapper valve having aperture sized to closely interfit the fuel discharge nozzle and thereby minimize the opening available for fuel vapor emission during refueling.
However, it is now required to provide for withdrawal of fuel from the tank through the filler tube in the event that in service removal of the tank is required after the initial assembly of the vehicle. The withdrawal of fuel from the vehicle tank is usually accomplished by insertion of a siphoning hose through the filler tube into the tank. However, where a check valve has been employed in the filler tube downstream of the flapper valve to prevent overfill or liquid escape during vehicle rollover it has been found quite difficult to push the end of the siphon hose through the check valve to the bottom of the fuel tank once the hose has entered the tank. It has been experienced that the end of the siphon hose lodges in the check valve.
It has thus been desired to provide a way of incorporating a check valve in a fuel tank filler tube such that it is easy to push a siphoning hose into the filler tube and through the check valve for withdrawal of fuel from the tank in the event that it is necessary to remove the tank from the vehicle for service. It has further been desired to provide such a siphonable filler tube check valve arrangement which is sufficiently low in manufacturing costs to be competitive in high volume automotive production and which is easy to assemble and install into the tank filler during manufacture of the tank and assembly into the vehicle.